[目的]研究宁夏东部荒漠草原优势植物细根分解对土壤碳矿化与土壤养分的影响,进一步分析优势植物细根分解动态与养分返还过程.[方法]以宁夏东部荒漠草原优势植物短花针茅(Stipa breviflora)与蒙古冰草(Agropyron mongolicum)细根为研究对象,设置对照(CK)、添加短花针茅细根(Sb)与添加蒙古冰草细根(Am)3种处理,采用室内培养法研究细根分解特征及其对土壤碳矿化与土壤养分的影响.[结果]连续培养61 d后,添加短花针茅和蒙古冰草细根显著增加土壤24 h CO2释放总量、分解初期(前14 d)土壤碳矿化速率与累积CO2释放量(P＜0.01).添加短花针茅与蒙古冰草细根使土壤激发效应显著增加(P＜0.01),增幅为40.50％与35.28％.与CK相比,添加短花针茅和蒙古冰草细根显著增加土壤硝态氮含量(P＜0.01),对土壤速效磷无显著影响.细根纤维素含量、m(C)∶m(N)与24 h CO2释放总量呈显著负相关(P＜0.05);细根碳含量、木质素含量、m(木质素)∶m(N)与24 h CO2释放总量呈显著正相关(P＜0.05).细根木质素含量、m(木质素):m(N)与累积CO2释放量呈显著正相关(P＜0.05).细根碳含量、氮含量、纤维素含量、m(N)∶m(P)与细根损失率呈显著正相关;细根木质素含量、m(木质素)∶m(N)与细根损失率呈显著负相关.[结论]植物细根初始化学性质是影响荒漠草原土壤有机碳矿化与养分循环的重要因素之一.
Effects of dominant plant fine roots decomposition on soil carbon mineralization and soil nutrients in desert steppe
[Objective]The study aimed to analyze the effect of dominant plant fine root decomposition on soil carbon mineralization and soil nutrients to further reveal the underground ecological processes in desert steppe.[Method]Fine roots of Stipa breviflora and Agropyron mongo-licum were selected in the study.There were three treatments including control(CK),S.breviflora(Sb)and A.mongolicum(Am).An incu-bate method was used to test the effects of fine roots decomposition on soil carbon mineralization and soil nutrients.[Result]S.brevifloris and A.mongolicum fine roots additions significantly increased 24-hour CO2 reflux,the soil carbon mineralization rate at the initial decomposition stage(first 14 days),and cumulative CO2 reflux(P＜0.01).Fine roots additions increased the soil priming effects by 40.50％and 35.28％,respectively(P＜0.01).S.brevifloris and A.mongolicum fine roots inputs significantly increased soil NO3--N content(P＜0.01),but had no significant effect on soil available P content.cellulose content and m(C)∶m(N)of fine root were negatively correlated with 24-hour CO2 reflux(P＜0.05).The carbon content,lignin content and m(lignin)∶m(N)in fine root were positively correlated with 24-hour CO2 re-flux(P＜0.05).The lignin content and m(lignin)∶m(N)of fine roots were positively correlated with the cumulative CO2 release(P＜0.05).Fine root carbon content,N content,cellulose content and m(N)∶m(P)were positively correlated with the fine root loss ratio;The lignin content,m(lignih)∶mn(N)of fine roots were negatively correlated with the loss ratio of fine roots.[Conclusion]The initial chemical properties of plant fine roots are one of the important factors changing the decomposition and nutrient cycling of fine roots in desert steppe.
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